Electric motor



ELECTRI C MOTOR ori inal F le Dec- 15. 1922 mvzufon ATT N EY.

Patented Apr. 7, 1931 UNITED STATES, PATE NT. OFFICE ALFRED OSWALD, 0FHACKENSACK, NEW JERSEY, ASSIGNOB TO UNDEBWOOD ELLIOTT FISHER COMPANY, OFNEW YORK, N. Y., A CORPORATION 01 DELAWARE ELECTRIC MOTOR Originalapplication filed December 18, 1922, Serial No. 606,575. Divided andthis application filed November 24, 1926. Serial No. 150,592. RenewedOctober 10, 1928.

This invention relates primarily to motors which are alterable for usewith either alternating or direct current, and to work in circuitshaving different fre uencies, etc.

The invention relates particularly to the construction of an annularfield-magnet core for said motor. To facilitate the assembly or removalof pro-wound field-coils, the core consists of separable portions. Eachcoreportion is laminated and provision is made for uniform laminationsor punchings for both cores.

Means for holding the two core-portions together may consist simply of atight sleeve fitting around theassembled core-portions and pressing themfirmly together in a direction substantially normal to the joints tosecure a good magnetic bond at said joints. Besides the fact that theabutting surfaces of two core-portions are directly pressed together,that is to say, from diametrically opposite directions, to secure a goodmagnetic bond, said good bond is further assured because the core ismade up of only two portions, that is to say, only two joints need bemade, one joint at each pair of abutting legs of the semi-annularcore-portions. To furthe: conduce to a good magnetic bond, each U-shapedpunching may have a V-point or taper at the end of one extremity or leg,and a V -recess or socket on the other leg. In each core-portion everyalternate punching may be reversed, so that, in the assembly, the pointsof each core-portion alternate with the recesses. The built-up halves ofthe magnet may then be assembled and form dovetailed joints, the pointsof each half fitting in the recess of the other half, and the jointsoverlapping, making an excellent magnetic joint, safeguarding the magnetagainst ordinary rough usage, preventing relative dis lace-' ment of thecore-portions, and permitting the poles to approach closely to thearmature with reduced liability of collision.

The use of acoreretaining casing or sleeve surrounding the core andholding its semiannular portions firmly together through pressureapplied substantially from diametrically opposite-directions obviatesthe need for using bolts or similar devices passing transversely throughthe laminations to clamp the overlapping portions of laminations of theopposite core-halves together. While the latter method of clamping thecore-halves together may secure a good magnetic joint, its applicationis apt to be unfeasible for some types of motors, as, for example, themotor herein shown, which, on account of its desired compactarrangement, afiords little or no room for such transverse fastenings. Y

Another feature of improvement relates to cleft pole-pieces of thefieldma net core, and to provision for placing the fiel -coils in suchrelation, to the cleft pole-pieces as to balance or take care ofa'rmature reaction. This feature has a special benefit where thefieldcoils are to be connectible in either series, or parallel, ormultiple series.

This application is a division of my application, Serial No. 606,575,filed December 13, 1922 (now Patent No. 1,713,617, dated May 21, 1929).

Other features and advantages will hereinafter appear.

In the accom anying drawings,

Figure 1 is a iagrammatic elevation of a motor embodying the presentimprovements in one form, the frame and certain parts being shown insection.

Figure 2 is a sectional elevation of the upper portion of a motorembodying certain of the improvements in another form, with the fieldcoils placed directly upon the polepieces, instead of upon the necks ofthe field magnet as at Figure 1.

In order that the utility of the invention may be readil understood abrief description of the erein-shown motor will at this point be 'venand will be followed by a description 0 the field-magnet core to whichthe invention particularly relates. It will be understood that theinvention is not limited to the particular motor shown but mayadvantageously be applied to other types of motors.

The motor-shaft 40 carrying an armature 41 is journaled in bearingscarried by the framework, which includes a barrel, drum or casing 46;said casing having the usual ends and advantages .cause serious sparkingwhen the motor is used on direct current, the armature coils,short-circuited by said auxiliary brushes as they span ad a'centcommutator se ments, are caused to be in a weak field, so that thecurrent induced in said last-mentioned armature coils andconsequentlythe sparkin are minimized.- The opposite poles of theeldmagnet are therefore divided each by a cleft 58. Thus one poleincludes parts 53 and 53" and the other pole includes parts 54: and 54.The armature coils short-circuited by auxilisry brushes 48 may be causedto pass the clefts 58 at the moment of said short-circuiting and therebyminimize sparking. Fieldcoils 49-52 are connectible in series, parallel,or seriesarallel in respect to each other but, in genera are in shuntrelation to the arms.- ture. Auxiliary field-coils 66-73 are alsoconnectible in various ways in respect to each other but, in general,are. in series relation to the armature and may oppose or assist coils49-52.

For compacting the motor an annular field core shape is selected. Allthe field-coils are pre-wound, and the resent invention provides foreasy assemb ing or removal of said coils upon or from said annular core,which is built 11 of laminationswhich ma be held together y rivets 61.To this en the annulus 55 is made in two parts, joined refer ably atwhat is suhstantiall a plane t rough the axis of the core, or, in ot erwords, a lane midway between the opposite pole aces.

Thus each semi-annular core-portionis sub-,

stantially U shaped with the aforesaid cleft poles between extremitiesor legs 59 of the U.

'From Figure 1 it will be seen that the prewound field-coils maybereadily threaded over said legs of the semi-annular core-portions. Thecoils 49-52 surround necks 56 of the core, said necks joining the cleftpole parts to the legs 59. Said ole parts are oined by necks 57 formingt e middle portions of the semi-annular core-portions. The

' clefts 58 of the poles may be of such shape that a coil may be placedaround the salient body of any one of the pole parts 53-53 or fi e-54,as indicated b the dotted line 60 (Fi re 1 said dotte line representinga fiel -coil in such position. Thus one coil may be placed around theneck 56 and an-.

other coil around the salient pole part to compensate for fielddistortion, and thereby conduce to uniform flux density across the polefaces in alternatin current operation. The auxiliary coils 66- 3surround the legs 59 of the annulus. Figure 2 shows another form ofannulus, in which the coils are all placed around the salient cleftpicle parts no coil-receiving necks as 56 of igure 1 being provided.

The annulus is divided into only two portions so that only two ointsneed be made, a minimum for the number of joints to be made conducing toa good magnetic circuit. Dividing and oining the core at a plane throu hthe core-axis makes possible the use of uniformlaminations or punchings.The laminations of the opposite core-portions may overlap at the joints62, such overlapping being affected, while still providing foruniformity of the punchings, by having the end of one leg of eachU-shaped punching extend beyond the plane at which the corehalves arenominally joined while the extent of the other leg falls correspondinglyshort of said plane. Thus, by reversing the punchings, a short leg abutsalong leg in each pair of punchings which form the completed annularlamination. The aforesaid overlapping of the opposite core-laminationsis then effected by reversing alternate pairs or groups of pairs oflaminations. c

The shapes of theends of the legs may be made so as to effectinterlocking of the pairs of laminations transversely of the motoraxis.The shape of the end of one leg of each punching is therefore referablyin the form of a V or taper 62, w ile the shape of the other leg-end'isthat of a V-recess or socket 62".

Inasmuch as the joints of the magnet-coreportions are surrounded bycoils 66, 73, it is unfeasibl'e to fasten the two built-u coreportionstogether by means of bolts t rough the overlapping portions of thelaminae. The motor-casing 46 is therefore resorted to as a means forholding the two core-portions together. By making said casing a tightsleeve fitting over the annulus, as indicated at 63, the portions ofsaid annulus are forced together from diametrically opposite directionsso that they are rigidly held and cause the end-surfaces of the oppositeleg-members 59 to firmly abut and thereby form two good magnetic bonds.Interlocking means between the annulus and casing may be provided toinsure against their relative rotation. Keepers 75, which complete amagsplitting said sleeve to permit its expansion and contraction forfacilitating insertion of the core and for positive clamping of thesame.

Variations may be resorted to within'the scope of the invention, andportions of the im rovements may be used without others.

aving thus described my invention, 1 claim:

1. In an electric motor including a series of pre-Wound field-coils, thecombination of substantially semi-annular or U-shaped halfcores, theleg-members of each thereof abutting the leg-members of the other, saidleg members surrounded by said pro-wound coils, and means to fasten saidhalf-cores rigidly together in said abutting relation to form twosatisfactory magnetic bonds, one at each of the abutments, saidfastening meansinclucling a fastening sleeve fitted around saidhalfcores and forcing them together in diametrically opposite directionsto form a complete built-up annular laminated magnetic core, eachhalf-core being formed of U-shaped laminations, each of which isintegral, said legs surrounding the armature of the motor.

2. In an electric motor including a series of pro-wound field-coils, thecombination of substantially semi-annular or U-shaped halfcores, theleg-members of each thereof abutting the leg-members of the other, saidlegmembers surrounded by said pre-wound coils, and means to fasten saidhalf-cores rigidly together in said abutting relation to form twosatisfactory magnetic bonds, one at eachof the abutments, said fasteningmeans including a fastening sleeve fitted around said halfcores andforcing them together in diametrically opposite directions to form acomplete built-up annular laminated magnetic core, each half-core beingformed of U-shaped laminations, each of which is integral, said legssurrounding the armature of the motor, the four legs of said half-coresbeing formed to interlock end to end.

3. In an electric motor including a series of pre-wound field-coils,'thecombination of substantially semi-annular or U-shaped halfcores, theleg-members of each thereof abutting the leg-inembers of the other, saidleg members surrounded by said pro-wound coils, and means to fasten saidhalf-cores rigidly together in said abutting relation to form twosatisfactory magnetic bonds, one at each of the abutments, saidfastening means including a fastening sleeve fitted around saidhalf-cores and forcing them together in diametrically oppositedirectionsto form a complete built-up annular laminated magnetic core,each half-core being formed of U-shaped laminations, each of which isintegral, said le s surrounding the armature of the motor, t e legs ofeach of" said half-laminations being formed with co operative taperingand socket ends to effect interlocking of each half-lamination with itsmate.

4. In an electric motor including a series ing a fastening sleeve fittedaround said halfcores and forcing them together in diametricallyopposite directions to form a complete built-up annular laminatedmagnetic core, each half-core being formed of U-shaped laminations, eachof which is integral, said legs surrounding the armature of the motor,the legs of each of said half-laminations being formed with co-operativetapering and socket ends to effect interlocking of each halflaminationwith its mat-e, each half-lamination having one leg formed with atapered point, and the other leg with a socket point to match, wherebyboth of said half-cores are built up of duplicate laminationsthroughout, the laminations in one half-core being reversed relativelyto those in the other halfcore, so that the points of each half-core areset into the sockets of the other half-core.

5. In an electric motor including a series of pro-wound field-coils, thecombination of sub stantially semi-annular or U-shaped halfcores, theleg-members of each thereof abutting the leg-members of the other, saidlegmembers surrounded by said pro-wound coils, and means to fasten saidhalf-'coresrigidly together in said abutting relation to form twosatisfactory magnetic bonds, one at each of the abutments, saidfastening means including a fastening sleeve fitted around saidhalfcores and forcing them together in diametrically opposite chrectionsto form a complete build-up annular laminated ma etic core, eachhalf-core being formed 0 U-shaped laminations, each of which isintegral, said legs surrounding the armature of the motor, the legs ofeach of said half-laminations being formed with cooperative tapering andsocket ends to effect interlocking of each halflamination with its mate,each half-laminapoint, rind the other leg with a socket point to match,whereby both of said half-cores are built up of duplicate laminationsthroughout, the laminations in one half-core be'n reversed relatively tothose in the other halfcore, so that the points of each half-core areset into the sockets of the other half-core, the laminations of eachhalf-core being alternatel reversed to effect overlapping jointsthroughout the magnet.

tion having one leg formed with a tapered 6. In an electric motor, afield-structure 1- ing of semi-annular or U-shaped half-portions joinedat substantially a plane through the axis of said core, the joints beingformed by means of corresponding taper and socket formations at the endsof the several laminations, each half-portion having a cleft pole, eachpart of said cleft pole being joined to one leg of the U by acoil-receiving neck or loop onto which a pie-wound coil may he slippedby threading it over said leg, each part of the cleft pole being soformed that the salient body thereof formed between the cleft and theaforesaid loop may also receive a pre wound coil, and core-retainingmeans where- 15 by said half-portions are embraced and pressure isapplied at said ]Ol!1l3S to form a satisfactory magnetic bond, saidpressure being substantially perpendicular to the aforesaid plane atwhich the core-portions are joined. 7. An annular field-magnet corebuilt up solely of alternately reversed duplicate semiannular orU-shaped laminations, said laminations forming built-up U-shapedhalfcores, which may be separated from each 25 other to thread pre-woundcoils over the legs thereof, said half-cores being joined to form thecomplete annulus, in which the leg-ends of one-half portion abut thelegends of the opposite half-portion, at their edges, means 39 formaintaining the edges of thelaminations together under pressure byapplying a force I perpendicularly to the plane of separation betweenthe half-cores, each annular lamination consisting of duplicate abuttingU-shaped 5 parts, the legs of the U-shaped laminations having theirabutting tips formed with protruding extensions and correspondingrecesses, said extensions and recesses matching and interlocking byreason of the reversing of the U-shaped laminations one in respect tothe other.

8. Field-magnet as set forth in claim 7, in which alternate annularlaminations are also bodily reversed, so that the leg-extensions ofadjacent annular laminations overlap and form a satisfactory magneticbond.

ALFRED E. OSWALD.

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